Conventionally, conveying apparatuses are known that sort conveyed items such as postal items according to a predetermined classification. This type of conveying apparatus separates and takes out the conveyed items one by one from a take-out unit, conveys these items spaced apart from one another with a conveyor belt or the like, and collects the items in a collecting unit. Here, there are individual differences in the thickness of conveyed items. Therefore, the conveying speed of each item may change depending on these individual differences. When the conveying speed changes in this way, the spacing between conveyed items may become too wide or too narrow. Thus, there is the possibility that during the operation of sorting or collecting the conveyed items, problems occur and a stable collection cannot be achieved.
For this reason, a gap correction device for adjusting the conveying speed of the conveyed items is provided midway in the conveyance of the conveyed items. By adjusting the conveying speed of the conveyed items with this gap correction device, the gap (referred to as “preceding gap” in the following”) between a conveyed item whose gaps are to be corrected (also referred to as “conveyed item subject to correction” in the following) and the conveyed item that is conveyed immediately before that conveyed item subject to correction (referred to as “preceding conveyed item” in the following) can be corrected. Moreover, the gap (referred to as “following gap” in the following”) between the conveyed item subject to correction and the conveyed item that is conveyed immediately behind that conveyed item subject to correction (referred to as “following conveyed item” in the following) can be corrected.
There may be individual differences in the length as well as the thickness among conveyed items. Here, when providing the gap correction device midway in a conveying path, the interval between the conveyor belt and a gap correction value needs to be determined based on the shortest conveyed item in order to enable delivery of the conveyed items from the conveyor belt to the gap correction device. However, conversely, a long conveyed item may cause a state where a rear end of this conveyed item in the conveying direction is still present on the conveyor belt even when a leading end of the conveyed item in the conveying direction has reached the gap correction device. In this case, the preceding gap and the following gap cannot be corrected, and moreover, there is the possibility that an excessive stress is exerted on the conveyed items, resulting in a decrease in the quality of the conveyed items.